It was a sunny Saturday afternoon, March 24, in the Sierra Nevada foothills of Central California as Mike Turner and a friend rode their mountain bikes down a rocky, narrow trail alongside a creek embankment.

The 28-year-old Turner, who grew up in Durham, was on a day off from his seasonal job as a science technician testing water and air quality at Sequoia National Park. Turner had biked down the trail many times before. But this time, the trip would change his life and plunge him into medical debt that could easily top $100,000.

Turner has no health insurance. He is in a class of young, healthy Americans without coverage that many in the health care industry call the "young invincibles." They are at the center of a U.S. Supreme Courtdebate regarding federal health care reform and whether the government can mandate health insurance.

"We were going through a slow, little technical section," Turner said of the accident last month. "I made a little folly. I steered just a little far left, and I caught my front wheel on a rock."

He started to lose his balance, and tried to free his shoes from the bike-pedal clips.

"My right foot, I couldn't get it out quite in time, and I tipped over and sort of free-fell down this embankment and landed on my face on this little, fallen tree," he said. "It just sort of hit me right across the jaw."

He knew immediately that something was horribly wrong. It felt like a golf ball was in his head. He was panicky. There wasn't, however, a lot of blood — just some below his right ear lobe, in an area unprotected by his helmet.

What he didn't know at the time was that a 4.5-inch-long stick, a quarter-inch in diameter, had impaled his head, jabbing into a cranial nerve that controls movement in the right side of his face.

"The stick actually came to rest indenting my jugular vein," Turner said he learned later from one of his surgeons. "It was very, very close to going in there, and it would have been 'lights out.'"

The injury hadn't affected his ability to walk. So, he and the friend took their bikes to the end of the trail and met up with Turner's girlfriend, Gayle, who was getting off work at nearby Sequoia National Park to get a ride to a hospital.

Turner's initial shock wore off and a jarring pain took over as he rode in his girlfriend's vehicle from the town where he lives, Three Rivers, Calif., to Kaweah Delta Medical Center in Visalia, Calif.

"I thought I had broken my jaw," Turner said.

After an assessment in Visalia, he was transferred to Community Regional Medical Center in Fresno, a trauma facility.

Turner went through several diagnostic imaging tests for hours — CT scans and MRIs. The surgeon broke the news that the end of a stick went straight into his head very close to his brain.

Turner's mother, Jane Milardo, lives in Niantic, Conn., about 3,000 miles from her son.

Her phone rang about midnight, which was 9 p.m. Saturday in California. Milardo answered, and it was a woman's voice — Turner's girlfriend.

"I thought, 'Oh my God, who is this calling me on Michael's cellphone?'" Milardo said. "She told me what happened and I was numb. It's the phone call in the middle of the night that everyone hopes they never get."

Too Pricey

Turner was in the Fresno hospital on Monday, March 26, without health insurance and facing a complicated surgery from a freak accident.

On the same day, theU.S. Supreme Courtbegan three days of discussions considering a challenge from 26 states to a key component of federal health care reform passed in 2010 — the "individual mandate."

The mandate would require people to have some kind of health insurance starting in 2014, with the purpose of adding young, healthy people — like Turner — to the individual health insurance market. As the economic theory goes, adding healthy people to the risk pool could reduce the price of health insurance and make individual health insurance more affordable to people who don't have coverage through an employer or the government.

"Michael is normally a happy guy," Milardo said. "He's always active. He skis. He participates in martial arts. ... Young people tend to think they're immortal. They don't think something can get to them — until it does."

Many health insurers argue that without a mandate and a sufficient penalty, young, healthy people who don't have coverage will forgo buying a health plan on the individual market. As a result, only those who require medical attention will buy coverage, driving up the cost to insurers and the price to customers.

When uninsured people like Turner have huge medical debts and don't pay their bills, hospitals cover the cost and, in turn, charge higher prices to those who do have health insurance. Health insurers call the phenomenon a "cost shift."

Turner suspects that he might have been able to afford coverage had a mandate been in place, as long as it actually had reduced premiums to an amount that he could afford.